The goal of the fourth and fifth years of the MENTOR project is to complete implementation and evaluation of a prototype computer-based system for monitoring drug therapy in hospitalized patients. MENTOR consists of several modules (Medical Knowledge Base, Evaluation Module, Patient Database Module, Advisory Module) interfaced through the Patient Database Module to a Hospital Information System from which the data needed for therapeutic monitoring is acquired. The initial two interfaces will be to the Palo Alto Veterans Administration DHCP System and to the Stanford University Medical Center Hospital Information System (SMIS). After implementation of the interfaces, the specific aims of the ongoing program are: 1) to assess the accuracy, sensitivity and specificity of advisories generated under a variety of conditions; 2) to refine the Medical Knowledge Base utilizing, in part, the information from 1); 3) to carry out a formative evaluation of the MENTOR system at Stanford Medical Center and the Palo Alto VA Medical Center; 4) to perform a summative evaluation of the impact of MENTOR on process variables and patient outcome at one site; and 5) to improve MENTOR system hardware and software configurations. These activities involve collaborative efforts by faculty from the Division of Clinical Pharmacology at Stanford, the University of Maryland School of Pharmacy, and the Laboratory for Computing and Cognition at the University of North Carolina.